For organic light emitting diode (OLED) devices, the laser ablation process has been used to remove organic films from unwanted areas of the device substrate. The first steps in the fabrication of OLED devices are the growth and patterning of the anode and leads films. The anode film is typically indium tin oxide (ITO), and the leads may include a tri-layer sandwich including an adhesion layer and a low-resistivity conducting layer. A typical lead structure is Cr/Cu/Cr. After forming the patterned anode and lead layers, the process involves patterning photoresist cathode separation lines followed by the coating of two or more organic layers, called the charge transport layer(s) and the electroluminescent layer(s), over the entire substrate using a liquid deposition technique. The substrate then goes into the laser ablation system, where the laser beam is focused onto areas that need to be cleared of the organic layers. These include the cathode-to-leads electrical contact pads, bond pads, and the frame (sometimes called rail) around the active area upon which glue is dispensed for the encapsulating lid.
It has been found that the laser ablation process can crack or otherwise damage the lead structure. Moreover, if a plastic substrate is used, the laser ablation process also can damage the moisture and oxygen barrier layer that is part of the substrate. It has also been found that corrosion of the leads can occur in the finished organic electronic device. Lastly, it can be difficult to adequately remove the organic layers over the leads to provide good electrical contact, as well as safely remove the organic layers over the barrier layer at the rail so that the finished organic electronic device can be properly sealed.